Is there an easy way to test a 940's oil pressure? I have a little valve chatter until the oil reaches the valves. I thought it was due to a cheap oil filter, which didn't have a by-pass valve. But not so. It doesn't do it when it's cold and the oil is thick. So I switch to a 10w40 oil and I thought that solved it but it's still doing it. Maybe a 50w? Or maybe I have low oil pressure(weak pump). Any easy way of testing that? Thanks.

 

I don't know if the 940 is the same as the 740 but if you look near the oil filter you will see a oil pressure sensor with 1 wire coming out of it. This is the sensor that triggers the low oil pressure and works at around 5-10 PSI. If you want to check oil pressure then remove this sensor and install a oil pressure gauge. If the oil pressure warning light is not red at idle then you have sufficient oil pressure. with a gauge you can check it when you raise the rpm's . Also I believe the reason for a by-pass valve in a filter is so when the filter gets clogged the by-pass valve opens and lets oil circulate through the engine.

 

Thanks for the info. IPD did tell me that Mann filters also allow oil to by-pass the filtering system to get oil quickly thru the engine. My light never comes on but that valve chatter is annoying when it's warm. It takes 30 seconds for oil to reach the valves and quite down. I don't know if that's normal. I want to test the oil but I don't want to buy a gauge for a 1 time use. Orileys and Autozone lend fuel gauge testers, would that work?

 

When was the last time the engine had a tune up. These engines with over head cam need a valve adjustment periodically. There are no "lifters" that become noisy because the cam makes contact with the valve tappet. How do you know the valve area does not get oil. Try looking in the oil fill cap in the morning while someone starts the engine. There should be oil in there . Also as the engine heats up it expands so the noise you hear may not be associated with low oil pressure but some other mechanical noise. It appears you have limited diagnostic's skill so for that reason I would suggest you seek a mechanic if you consider this a problem. If your low oil pressure light does not come on at idle then you should have sufficient oil pressure.

 

The valves we're adjusted less than 20,000 miles ago, which for this engine should be a long time before it needs another. And if it was the valves they'd probably do it continuously. Since my light doesn't come on I assume the pressure's right but want to check it out of curiosity and see if it fluctuates at all when warm and higher rpm. When it's cold no noise. When it's hot and I turn off, then restart within say 2 or 3 minutes again no noise. It's only when I wait longer and most of the oil drains back to the pan and then restart that I hear the valves. And 30 seconds later or a quick blip of the throttle and quiet again. UPDATE: I just dumped a can of STP in, and if anything's going to thicken the oil that will, No difference. My new theory is that maybe the valve "hushers" wore out and fell off, which will increase the gap and the oil, when it gets there is filling in that extra space. I'm going to pull the cover and check the gap.

 

OK I'm game so what's a "husher" ????

 

Check it out:


https://volvoforums.com/forum/volvo-...hushers-56715/


and buy em here:


Valve Absorber (Husher) GENUINE VOLVO 113329 1219648 3514432 3514432V

 

pull the plug on the front of the block and install guage

 

OK I know of the absorber but didn't hear of the term husher. If you have bad , dried out absorbers then they would be noisy all of the time so this would not solve your problem. When did the noise start. I picked up the piston slap/ rod knock noise at about 150K miles and at times it idles like a diesel but it's still running at 353K. When it blows I'll rebuild it.

 

The hushers won't help you. You need a valve adjustment done correctly--it is a bit tricky and just because it was done 20k ago, doesn't mean a thing!

 

I think you're right. If it was the hushers it would do it all the time - cold idle and hot idle. It's definitely not piston slap, which occurs when it's cold and disappears when the engine warms up and expands. My noise is directly related to lubrication - or lack of. I'm thinking now that it's a weak pump. When the engine's cold and tolerances tight the pump moves the oil no problem. When the engine warms and tolerances expand the pump doesn't move as much oil and takes 30 seconds to reach the valves. The only question is why doesn't the dash light come on? I checked the service records from the previous owner and they did have the light come on at 116,000 miles and the oil pump was replaced. Back to square one - I need to check the oil pressure.

 

Is that the same place the sensor is? And what's an average pressure at idle and 3,000 rpm? Thanks

 

I am going to do it and check the oil pressure. It's got to be one or the other?

 

15-20psi at idle with hot oil (10W-30 or 10W-40). At 3000 rpm I would say around 40 psi.

 

Well good news: I don't think my pump is bad. Cold idle - 20lbs, cold at 2000 rpm - 50 lbs. Hot idle - 18 lbs, hot at 2000 rpm - 46 lbs. So the next step is to check the valve clearance. It kinda makes sense now that "loose" valves would quiet as more oil filled the void. I'll update after I check that. And thanks Revolv for the tip on accessing the front plug. That was a lot easier than pulling the sensor.

 

Adjust hot? or cold?

 

You we're right. I have 3 valves that are within specs at .016, the other 5 are anywhere from .017 to .019, which I assume is enough for some valve clatter. The last adjustment was done at the dealer and less than 20,000 miles ago. Hard to figure why the dealership screwed up?


And the hushers are trash...hard as a rock, flattened and some have half missing. Obviously they're original and the dealer didn't even bother checking them. If it was me, I wouldn't have paid the bill.